The use of sensor actuated security lighting is well known. These lighting systems are typically disposed around an entrance or front door area of a building or property. A microwave or infrared sensor is connected to one or more lights so that once a sensor is triggered by movement or the presence of body heat, the light is actuated. Usually, the light(s) remain on for some predetermined period of time.
These lighting systems not only provide some level of security, they are also useful for automatically actuating the lights in a dark environment when a person may not be able to see clearly or have access to necessary switches to actuate the lights. It is for this reason sensor lights are often found around entry ways. Of course, such sensor lights also serve the purpose of providing the illusion a building or property may be occupied when it is not.
Other known lighting systems include photovoltaic switching systems which sense the ambient light levels and if these levels fall below a predetermined threshold value, lighting is automatically switched on. Systems using photovoltaic switches are often used together with security lighting but are perhaps most well known in flashing orange roadside lamps. In these systems, once the level of ambient light reduces below a predetermined level, the light comes on until the ambient light increases back to that predetermined level in which case the lighting switches off.
Whilst the ability for lights to be able to be turned off and on in response to motion or ambient light conditions is desirable in many circumstances, there are many applications in which whilst useful, such is not ideal. For example, under Australian Building Standards, fire escapes must have a minimum level of emergency lighting intensity at all times. This level of lighting is dimmer than general security lighting as the fire escape stairs need only be lit brightly enough to provide adequate vision to allow emergency egress. Fire escapes are often also used as a means of moving between floors of a building and for this, the Australian Building Standards require a higher level of lighting than emergency lighting.
As such, standard lighting is provided that is maintained continuously. Many fire escapes are known to have at least some natural light ingress, however, this rarely provides sufficient light intensity for the entire fire escape and continuous lighting provides that minimum intensity for the darkest points. This usually requires constantly lighting an entire fire escape.
In the case of car parks, for example, a minimum level of security lighting is required. Often, natural lighting can be insufficient in some locations to provide the minimum level. To err on the side of caution, however, security lighting providing a minimum level of light over an entire car park is installed. This level of light need not be sufficient to read a book or the like but to simply allow people to discern figures and movement.
In the case of vehicle and train tunnels, when travelling from bright daylight external to the tunnel into it makes a significant change in contrast occur. The tunnels have a minimum level of light intensity for security purposes but this is not always useful in the case of tunnels, especially those which intermittently break daylight.
The motion sensing of people or other events is not always desirable such as in fire escapes where a minimum level of lighting is required to allow a sufficient level of visibility to any potential users.
Genesis of the Invention
The genesis of the invention is a desire to provide a lighting system appropriate for use in car parks, tunnels, fire escapes or the like, or to provide a useful alternative.